A hermetic terminal of a refrigerant compressor is produced by sealing a metal stem and a metal pin to each other with a glass for sealing in order to maintain airtightness.
The glass for sealing is produced and used as described below. First, a glass raw material is melted and formed, and the glass after forming is pulverized in a ball mill and then allowed to pass through a predetermined sieve to provide fine powder. Next, granules are produced by mixing the fine powder with a binder and granulating the mixture. After that, the granules are subjected to tablet molding to produce a green compact having a through-hole, and the green compact is increased in temperature from normal temperature, to thereby decompose and remove the binder and sinter the green compact. Next, a metal pin is inserted in the through-hole of the resultant sintered compact, and the sintered compact is in turn housed in a circular metal stem, followed by being loaded into an electric furnace, and fired at a temperature higher than a glass transition point under a nitrogen atmosphere, to thereby seal the metal pin and the metal stem to each other. As a result, the glass for sealing is in a state of being compressed fey the metal stem. The metal stem generally has a thermal expansion coefficient of from 140×10−7/° C. to 150×10−7/° C. The metal pin generally has a thermal expansion coefficient of from 100×10−7/° C. to 110×10−7/° C. The glass for sealing generally has a thermal expansion coefficient of from 90×10−7/° C. to 100×10−7/° C.
FIG. 1A is a conceptual diagram for illustrating a hermetic terminal 1. The hermetic terminal 1 comprises a metal stem 11, a metal pin 12, and a glass 13 for sealing. FIG. 1B is a conceptual diagram for illustrating, with respect to a main portion of the hermetic terminal 1 of FIG. 1A, a state of the metal stem 11, the metal pin 12, and the glass 13 for sealing before firing. FIG. 1C is a conceptual diagram for illustrating, with respect to the main portion of the hermetic terminal 1 of FIG. 1A, a state of the metal stem 11, the metal pin 12, and the glass 13 for sealing after the firing.